1. Field of the Invention
This invention relates, in general, to a gas piston retrofit for a firearm and more particularly to a gas piston retrofit for automatic configured for installation on direct gas impingement automatic and/or semi-automatic firearms, as well as to methods for their installation and use.
2. Description of Related Art
Conventional automatic and semi-automatic firearms, such as the AR-15, typically use a direct gas impingement system to cycle the action of the bolt. Exemplars of such firearms relying on direct gas impingement include U.S. Pat. No. 4,765,224 to Morris, which discloses an automatic rifle gas system, and U.S. Pat. No. 6,971,202 to Bender, which discloses a gas-operated action for auto-loading firearms.
In such gas systems, when the rifle or firearm is fired, gas from the front of the barrel travels through a tube and into the bolt carrier key, the pressure of which gas drives the bolt carrier rearward, rotates and unlocks the bolt, allows the bolt to move back to eject a round and then move forward to feed another round. One problem with such gas impingement system is that un-burnt powder residue, products of combustion, and particulates are carried along with the gas. An accumulation of deposits fouls the action of the rifle or firearm and creates cycle problems resulting in loss of reliability.
Alternative gas piston systems have been devised and utilized in such firearms. Exemplars of such gas piston systems include U.S. Pat. No. 4,475,438 to Sullivan, which discloses gas operated, automatic or semi-automatic firearms, U.S. Pat. No. 5,351,598 to Schuetz, which discloses a gas-operated system, and U.S. Pat. No. 6,722,255 to Herring, which discloses an apparatus and method for actuating a bolt carrier group of a receiver assembly. While such systems may or may not alleviate accumulation of deposits, such systems require extensive modification for firearm retrofit. For example, the Sullivan firearms, the Schuetz system, and the Herring apparatus require radically redesigned receivers and front sights. Furthermore, the modifications required are generally incompatible with standard MIL-SPEC hand guards, and other accessories of the AR15/M16/M4 family of firearms, including, but not limited to rifles, machine guns and carbines.
While there are other designs on the market, such as those provided by Bushmaster Firearms International, Patriot Ordnance Factory, Inc., and Ares Defense Systems, Inc., such designs generally require a substantial investment (e.g., approximately US $1,000 or more) as such designs require redesigned receiver assemblies and/or other major components.
In light of the foregoing, it would be beneficial to have a gas piston retrofit assembly which overcomes the above and other disadvantages of known semi-automatic firearms. Moreover, it would be beneficial to have a relatively low-cost kit that is compatible with conventional direct gas impingement automatic and semi-automatic firearms